Tübingen 2003 – scientific programme
Parts | Days | Selection | Search | Downloads | Help
HK: Physik der Hadronen und Kerne
HK 16: Kernphysik/Spektroskopie II
HK 16.4: Talk
Tuesday, March 18, 2003, 16:45–17:00, A
Search for a new Shape Isomer in 239U* — •C. Alvarez1, P.G. Thirolf1, D. Habs1, H.J. Maier1, T. Morgan1, W. Schwerdtfeger1, and R.S. Simon2 — 1Ludwig-Maximilians-Universität München — 2GSI, Darmstadt
Experimental evidence exists from 238U(n,f) studies for the existence
of a so far unobserved shape isomer in 239U with an unusually low
ground state excitation energy of EII=1.700 MeV [1] and a halflife
of t1/2>250 ns. The γ back decay of this potential shape
isomer into the first minimum should be observable by in-beam γ-ray
spectroscopy [2].
In a first experiment at the Garching Tandem accelerator prompt and delayed
γ-rays following the 238U(d,p) reaction with a pulsed deuteron
beam (Ed= 11
MeV, pulse distance 1.6 µs) were detected in coincidence with protons.
At the neutron separation energy a much larger transmission through the
inner barrier is observed than expected from the parameters of the top of
the barrier, resulting in a good isomer population.
The goal was to study the population cross section and the halflife of the
potential shape isomer, using a large, radially segmented cylindrical NaI
detector prior to future high-resolution studies with the MINIBALL
spectrometer. First experimental results will be presented.
[1] S. Oberstedt et al., Nucl. Phys. A636 (1998) 129
[2] P.G. Thirolf and D. Habs, Prog. Part. Nucl. Phys. 49 (2002) 325
* Supported by the DFG and Maier-Leibnitz-Laboratorium, Garching